/****************************************************************************
 *
 * ftgasp.h
 *
 *   Access of TrueType's 'gasp' table (specification).
 *
 * Copyright (C) 2007-2019 by
 * David Turner, Robert Wilhelm, and Werner Lemberg.
 *
 * This file is part of the FreeType project, and may only be used,
 * modified, and distributed under the terms of the FreeType project
 * license, LICENSE.TXT.  By continuing to use, modify, or distribute
 * this file you indicate that you have read the license and
 * understand and accept it fully.
 *
 */

#ifndef FTGASP_H_
#define FTGASP_H_

#include <ft2build.h>
#include FT_FREETYPE_H

#ifdef FREETYPE_H
#error "freetype.h of FreeType 1 has been loaded!"
#error "Please fix the directory search order for header files"
#error "so that freetype.h of FreeType 2 is found first."
#endif

FT_BEGIN_HEADER

/**************************************************************************
 *
 * @section:
 *   gasp_table
 *
 * @title:
 *   Gasp Table
 *
 * @abstract:
 *   Retrieving TrueType 'gasp' table entries.
 *
 * @description:
 *   The function @FT_Get_Gasp can be used to query a TrueType or OpenType
 *   font for specific entries in its 'gasp' table, if any.  This is mainly
 *   useful when implementing native TrueType hinting with the bytecode
 *   interpreter to duplicate the Windows text rendering results.
 */

/**************************************************************************
 *
 * @enum:
 *   FT_GASP_XXX
 *
 * @description:
 *   A list of values and/or bit-flags returned by the @FT_Get_Gasp
 *   function.
 *
 * @values:
 *   FT_GASP_NO_TABLE ::
 *     This special value means that there is no GASP table in this face.
 *     It is up to the client to decide what to do.
 *
 *   FT_GASP_DO_GRIDFIT ::
 *     Grid-fitting and hinting should be performed at the specified ppem.
 *     This **really** means TrueType bytecode interpretation.  If this bit
 *     is not set, no hinting gets applied.
 *
 *   FT_GASP_DO_GRAY ::
 *     Anti-aliased rendering should be performed at the specified ppem.
 *     If not set, do monochrome rendering.
 *
 *   FT_GASP_SYMMETRIC_SMOOTHING ::
 *     If set, smoothing along multiple axes must be used with ClearType.
 *
 *   FT_GASP_SYMMETRIC_GRIDFIT ::
 *     Grid-fitting must be used with ClearType's symmetric smoothing.
 *
 * @note:
 *   The bit-flags `FT_GASP_DO_GRIDFIT` and `FT_GASP_DO_GRAY` are to be
 *   used for standard font rasterization only.  Independently of that,
 *   `FT_GASP_SYMMETRIC_SMOOTHING` and `FT_GASP_SYMMETRIC_GRIDFIT` are to
 *   be used if ClearType is enabled (and `FT_GASP_DO_GRIDFIT` and
 *   `FT_GASP_DO_GRAY` are consequently ignored).
 *
 *   'ClearType' is Microsoft's implementation of LCD rendering, partly
 *   protected by patents.
 *
 * @since:
 *   2.3.0
 */
#define FT_GASP_NO_TABLE -1
#define FT_GASP_DO_GRIDFIT 0x01
#define FT_GASP_DO_GRAY 0x02
#define FT_GASP_SYMMETRIC_GRIDFIT 0x04
#define FT_GASP_SYMMETRIC_SMOOTHING 0x08

/**************************************************************************
 *
 * @function:
 *   FT_Get_Gasp
 *
 * @description:
 *   For a TrueType or OpenType font file, return the rasterizer behaviour
 *   flags from the font's 'gasp' table corresponding to a given character
 *   pixel size.
 *
 * @input:
 *   face ::
 *     The source face handle.
 *
 *   ppem ::
 *     The vertical character pixel size.
 *
 * @return:
 *   Bit flags (see @FT_GASP_XXX), or @FT_GASP_NO_TABLE if there is no
 *   'gasp' table in the face.
 *
 * @note:
 *   If you want to use the MM functionality of OpenType variation fonts
 *   (i.e., using @FT_Set_Var_Design_Coordinates and friends), call this
 *   function **after** setting an instance since the return values can
 *   change.
 *
 * @since:
 *   2.3.0
 */
FT_EXPORT(FT_Int)
FT_Get_Gasp(FT_Face face, FT_UInt ppem);

/* */

FT_END_HEADER

#endif /* FTGASP_H_ */

/* END */
